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Патент USA US3082638

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March 26, 1963
A. B. JONES, JR., ETAL
3,082,629
ANTI-FRICTION SUPPORT MECHANISM
Filed Sept. 12, 1960
2 Sheets-Sheet 1
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FIG.1.
INVENTORS
ARTHUR BURTO/V JONES JR.
EDGAR H. LUBER
BY
ATTO NEY
hired ts
.iQ
-
Shh-82,629
Patented Mar. 26, 1%3
1
2
3,082,629
able torque about the output axis of the sensitive element.
ihNTL-FRICTIQN SUPPQRT MECHANHSM
In a preferred embodiment of the invention, means are
Arthur Burton Jones, in, Newington, Conn, and Edgar
provided for applying the force to the bearing balls by
H. Luber, Forest Hills, N.Y.; said Jones assignor to The
Fafnir Bearing Company, New Britain, Comm, a corpo
ration of Connecticut, and said Luber assignor to Sperry
Rand €orporation, Great Neck, N.Y., a corporation of
means of the bearing ball retainer.
it is a primary object of the present invention to pro
vide an improved anti-friction support mechanism for
sensitive elements.
it is an additional object of the present invention to
Delaware
Filed Sept. 12, 1969, Ser. No. 55,466
8 Claims. (Cl. 74—-5.4)
The present invention relates to anti-friction support
mechanisms for sensitive elements and particularly re
lates to anti-friction mechanisms or bearings for improv
ing the accuracy of sensitive instruments such as gyro
provide anti-friction support mechanism for gyroscopic
instruments ‘which materially improves the accuracy of
gyroscopic instruments.
It is a further object of the present invention to pro
vide an anti-friction support mechanism for sensitive ele
ments which includes means for substantially counteract
scopic instruments.
15 ing undesirable errors due to friction within the support
in extremely high accuracy devices, particularly gyro
mechanism and due to causes external thereto.
scopic apparatus, there is an increasing need for higher
These and other objects of the invention will become
accuracy instruments necessitating improvements in anti
friction support mechanisms, particularly those of the
rolling bearing type. In prior gyroscopic apparatus, the
wherein:
problem of drift of the gyroscope has been particularly
troublesome and extensive efforts have been previously
freedom gyroscope having a thrust bearing embodying
the present invention with parts of the drawing in eleva
made to minimize drift, as explained more fully in US.
tion;
apparent from the following description of the drawings
FIG. 1 is a longitudinal section of a single-.degree-of
I
patent application Serial No. 611,737, entitled, Anti
friction Support Mechanism for Gyroscopic Devices, ?led
FIG. 2 is a section taken along lines 2—2 of FIG. 1;
25
PK}. 3 is a longitudinal section of the lower portion
September 24, 1956 and now Patent No. 2,970,480 in the
of the singie-degree-of~r"reedom gyroscope of FIG. 1 hav
names of Zeigler et al. The present invention is an im
provement over the invention described in said US. pat
ent application Serial No. 611,737.
ing an angular contact bearing embodying the present
invention;
PEG. 4 is a bottom view of MG. 3; and
The present invention is a device which materially re 30
PEG. 5 is an enlarged longitudinal section of the re
duces the friction moments on a sensitive element, such
tainer 36 of PEG. 3.
as the sensitive element of a gyroscopic instrument, intro
While the present invention will be described as ap
duced by the support or suspension of said element and
plied to certain configurations of rolling bearing means
other friction inducing connections between the sensitive
in a gyroscope it is to be understood that this invention
element
its frame, such as slip rings. For purposes 35 is applicable not only to all types of rolling bearing means
of example, the present invention will be described in
but is also adaptable to appreciably reducing friction in
terms of a modi?ed thrust ball bearing. When a ball
devices other than in gyroscopcs.
bearing is loaded in thrust (a condition which exists, for
Referring now to FIG. 1, a preferred embodiment of
instance, when the axis of the bearing supporting the
the invention will be described with respect to a single
sensitive element is vertical or when a preload is applied 40 degree of freedom ,roscope 9 which is rotatably sup
to the bearing) the friction moments on the sensitive
portedto provide an output about its output or vertical
element introduced by forces established between the
bearing balls and the inner race (which is integral with
axis 1%. The gyroscope 9 has its gyroscopic rotor ill,
shown in dotted lines, mounted within a housing 13 for
the sensitive element) are quite high. In the case of a
spinning about a horizontal axis 12 that is perpendicular
gyroscopic instrument, for instance, these friction mo 4:5 to the vertical axis iii. The housing 13 is connected to
ments prevent the instrument from achieving the accu
a vertical gimbal 1d. The gyroscope 9 by means of its
racy required in modern inertial guidance systems.
vertical gimbal 14 is journalled for rotation about its ver
To reduce the e?ects of the aforementioned friction
tical axis Til within a frame 15 by means of spaced com
moments, the invention described in the above-mentioned
pound radial bearings lo and 1.7 and a thrust bearing 13.
50
US. patent application Serial No. 611,737 utilizes a com
The radial bearings 16 and 17 restrain the gyroscope 9
pound bearing which averages the friction torques by
rotating an intermediate race through several revolutions
?rst in one direction and then in the opposite direction.
However, when thrust loading as described above is used,
the torque created by rotating the bearing in one direction
is relatively high and the torque created by rotating it in
the opposite direction may not be exactly equal to the
first torque. This causes the average of these torques
to be high and varying with time, i.e., random.
One purpose of the present invention is to provide a
device which materially reduces to the point of substan
tially eliminating the aforementioned undesirable friction
moments by applying a force on the sensitive element
where the beari g balls contact the inner race which (a)
cancels the friction forces acting thereupon and (b) by
acting as a moment around the vertical axis or center
line of the sensitive element cancels or materially re
against radial shift while its weight is supported by the
thrust bearing 18. The compound radial bearings 16
and 17 are aligned coaxially With respect to the vertical
axis it} and are of the type more fully disclosed in the
aforementioned US. patent application Serial No.
61 1,737.
The radial bearing 16 has an inner race 2d integral
with the upper trunnion 2.1. of the gimbal 14, an inter
mediate race 22 and an outer race 23, the latter being
mounted on the frame 15. Bearing balls are disposed
between the races 20 and 22 as well as between the races
22 and 23‘. Similarly, the radial bearing 17 has an inner
race 24 integral with the lower trunnion 25 of the gimbal
14, an intermediate race 26 and an outer race 27, the
65 latter being mounted on the frame 15. Bearing balls are
disposed between the races 24 and 26 as well as between
the races 26 and 27.
duces all other friction moments acting thereupon. This
The thrust bearing 18 has an upper thrust plate 30
is accomplished in the present invention by means which
which acts as an inner race, a lower thrust plate 31 which
applies a force on the bearing balls of the bearing having 70 ‘acts as an outer race, bearing balls 32 disposed between
a magnitude and a direction which is transmitted to the
the plates 3% and 31, vand a ball retainer 33. The upper
sensitive element to substantially eliminate the undesir
thrust plate '30 is integral with the lower extremity of the
3,082,629
4
3
vertical gimbal 14 for supporting the gyroscope 9. The
lower thrust plate 31 is mounted on a rotatable lower
center of the yoke 63 is pivotally connected to the adjust
ing rod 64 ‘which in turn is slideably disposed in a projec
tion 70 of the frame 15. Moving the adjusting rod 64
thrust plate support 34 preferably by means of an O-ring
toward or away from the drag disc 52, as viewed in FIG.
35. The support 34 is mounted ‘for rotation about the
vertical axis 14} ‘by means of spaced bearings 36 and 37 01 2, reduces or increases the tension in the springs 61 and
62 thereby reducing or increasing respectively the re
which are mounted on the frame 15.
silient forces applied by the brake shoes 53 and 54 to the
To reduce the drift of the gyroscope, the friction
drag disc 52. A vernier adjustment of the position of the
torques are averaged as fully explained in the aforemen
adjusting rod 64 is obtained by the ?ne adjustment screw
tioned patent application Serial No. 611,737 ‘by rotating
65 which is threadedly disposed in a guide 71 which in
the intermediate races 22 and 26 of the radial bearings
turn is rigidly connected to the adjusting rod 64. An ex
16 and 17 and the lower thrust plate 31 of the thrust bear
tremity of the adjusting screw 65 bears against the pro
ing 18 through several revolutions ?rst in one direction
jection 70. A set screw 72 secures the adjusting rod 64
and then in the opposite direction with the intermediate
to the projection 70‘ when the ultimate position of the rod
races 22 and 26 being rotated in opposite directions with
respect to each other. To accomplish this the intermedi 15 64 is determined.
In operation, the gyroscope 9 remains substantially
ate race 22 has an extension thereof to which a spur gear
stationary while the frame 15 rotates with respect to it
40 is attached and the intermediate race 26 has an exten
about the vertical axis 19 to provide an output signal from
sion thereof to which the spur gear 41 is attached. Sim
the pick-oil 51. Although the friction due to the bearings
ilarly, a spur gear 42 is attached to an extension of the
16, 17 and 18 is greatly reduced by rotation of the inter
support 34. The gears 41 and 42 are rotated in the same
the gears 41 and 42 by means of spur gears 45 and 46 re
mediate races 22, 26 and the lower race 31 respectively,
as explained above, and as explained more fully in said
patent application Serial No. 611,737 there are still some
spectively while the gear 40 is rotated in the opposite di
friction forces remaining which result in undesirable drift
direction by means of a motor’ 43 which has its output
shaft 44 connected through reduction gearing 38 to drive
rection with respect to the gears 41 and 42 by a spur 25 of the gyroscope 9 thereby causing an undesirable output
from the pick-off 51. The friction moments acting on the
gear 47. The direction of rotation of the motor 43 is
gyroscope ? includes (a) the moment introduced by the
cyclically reversed after the races 22, 26 and 31 have com
friction force at the contact area of each of the balls 32
pleted several revolutions in one direction by means of
acting on the upper thrust plate 30 which in turn acts upon
a cyclic reversing mechanism 50‘.
As explained above, with thrust loading as described, 30 the gyroscope 9 through a moment arm equal to the dis
tance between the center of the contact area of each of the
the torque created by rotating in one direction is relatively
high and may not be exactly equal to the torque created
when rotating in the opposite direction. Further, the fric
balls 32 and the vertical axis 10 of the gyroscope 9, (b)
the friction moment introduced by each of the balls 32
sliding at their respective contact areas with the upper
ring connections 49 required to transmit power to spin 35 thrust plate 30 about an axis joining the center of the
contact area and the centers of the respective balls 32, and
the gyroscopic rotor 11, create ‘friction torques that act
(c) the friction moment introduced by external connec—
to provide an erroneous output about the vertical axis 10.
tions from the gyroscope 9 to the frame 15, for example
The undesirable torques appearing around the vertical
the friction due to the electrical slip rings. The rotation
axis 10 which cause an error in the output signal from
an output pick-oft 51 can be substantially eliminated by 40 of the support 34 causes the lower thrust plate 31 to rotate
with it which in turn results in rotation of the retainer 33,
applying countertorques to the vertical gimbal 14 around
and the drag disc 52.
the vertical axis 16. By introducing a slight drag on the
The adjusting rod 64 is positioned in order that the drag
retainer '33 of the thrust bearing 18 while its lower thrust
force applied by the brake shoes 53 and 54 to the drag disc
plate 31 is being rotated, countertorques can be induced
52 has a magnitude and a direction that results in the
which substantially cancel the undesirable friction torques
substantial cancellation of the net friction moments de
about the vertical axis 10. Due to the drag of the retainer
scribed above. The force applied by the brake shoes 53
33 on the balls 32 of the thrust ‘bearing 18 forces are in
and 54 due to the tension of springs 61 and 6-3 to the drag
troduced at the places where the balls 32 contact the
disc 52 is in turn applied to the retainer 33- to slow down
upper thrust plate 3%) which counteract the force of roll
the normal rotation of the retainer 33. Slowing down
ing friction normally acting at these places of contact.
the speed of rotation of the retainer 33 causes it to apply
The forces can be adjusted so that the undesirable torque
a force to the balls 32 having a magnitude and a direc
about the output or vertical axis 10 of the gyroscope 9 is
tion to substantially cancel out the net friction moments
reduced to substantially zero.
a
acting about the vertical axis 10 by causing the balls 32
One means for applying a drag on the retainer 33 of
the thrust bearing 18 is shown in FIGS. 1 and 2 where a 55 to apply an equal countertorque to the upper thrust plate
30 which is integral with the vertical gimbal 14 of the
drag disc 52 is coaxially and rigidly connected by being
gyroscope 9. This countertorque substantially eliminates
screwed, for example, to the retainer 33. A drag or force
tion caused by electrical connections, for example slip
the undesirable moments about the vertical axis 10
is exerted on the drag disc 52 by means of brake shoes
thereby substantially eliminating the drift error in the out
53 and 54 which are pivotally mounted on the frame 15
by means of pivots 5S and 56 respectively. The brake 60 put signal from the pick-off 51.
shoes 53 and 54 are disposed to bear against the periph
ery of the drag disc 52 at points on its periphery that are
diametrically opposed as shown clearly in FIG. 2. The
force applied by the brake shoes v53‘» and 54 to the drag
disc 52 is adjustable by a ‘force adjusting mechanism 60.
The force adjusting mechanism 60 includes helical
springs 61 and ‘62, a yoke 63, an adjusting rod 64 and a
?ne adjustment screw 65.
The spring 61 has one ex
By referring to FIGS. 3 and 4, the present invention
will now be described with respect to an angular contact
bearing 89 supporting a gyroscope 3 of the type described
with respect to FIG. 1 wherein like elements will be in
dicated by like reference characters. The angular con
tact bearing 80 comprises an inner race 81, an inner row
of bearing balls 82, an intermediate race 83, a double
outer row of bearing balls 84, an outer race 85, and a ball
retainer 86 separating the balls 82. The inner race 81
tremity connected to a pin 66 that is mounted on the
brake shoe 53 in spaced relation to its pivot 55. The 70 is integral with the lower trunnion 25 of the vertical gim
bal 14 of the gyroscope 9. In order to provide a drag
other extremity of the spring 61 is connected to an ex
tremity of the yoke 63. Similarly, spring 62 has one ex
force on the retainer 86, the retainer 86 has ‘an extension
87 that is cooperative with brake shoes 90 and 91.
tremity connected to a pin 67 that is mounted on the brake
As shown more clearly in FIG. 4, the brake shoes 90
shoe 54 in spaced relation to its pivot 56 with its other
extremity connected to an extremity of the yoke 63. The 75 and 91 contact the periphery of the extension 87 of the
3,082,629
retainer ‘86 at diametrically opposite points. The force
applied by the brake shoes 90 and 91 is adjustable by
means of adjusting screws 92 and 93 respectively. The
adjusting screws 92 and 93 are mounted within threaded
guides '94 and 95 respectively which in turn are mounted
on the frame 15. A spur gear 41 is connected to an ex
tension of the intermediate race 83 in a manner similar
to that described above with respect to intermediate race
6
tional electrical gyroscopic torquing device. Preferably,
when the invention is applied as a torquing device the
outer race, for example, the lower thrust plate 31 of the
thrust bearing 18 would be rotated unidirectionally and
would not have its direction of rotation periodically
reversed as described above.
Although the invention has been described with respect
to thrust and angular contact bearings, it is obvious that
2d shown in FIG. 1.
Preferably, as shown in FIG. 5, the retainer 86 has
canted holes 96 which receive the balls 82 and prevent the
retainer 86 from contacting either the inner race 81 or
it is equally adaptable to radial bearings.
the intermediate race 83 during operation.
limitation and that changes within the purview of the
While the invention has been described in its preferred
embodiments, it is to be understood that the words which
have been used are words of description rather than of
In operation, the intermediate race 83 is rotated in a
appended claims may be made without departing from
manner similar to that described with respect to the inter 15 the true scope and spirit of the invention in its broader
mediate race 26 of FIG. 1. The rotation of the inter
aspects.
mediate race 33 causes the retainer 86 to rotate with the
What is claimed is:
race 83. vBy adjusting the adjusting screws 92 and 93,
1. In combination, a sensitive element, means responsive
the brake shoes 90 and 91 respectively are adjusted to pro
to the movement of said sensitive element for providing
vide a drag force against the retainer 86 tending to slow 2-0 an output signal in accordance therewith, bearing means
it down. A fraction of this force is transmitted to each
supporting said element for rotation about an axis there
of the balls 32 and thus to the inner race 81. 'By suitable
of, said bearing means including an inner race, an outer
adjustment of the force applied by the brake shoes 96= and
race and rolling anti-friction members between said races,
9f, the drag on the retainer 86 can be adjusted to sub
means including said bearing means tending to apply an
stantially eliminate the net friction moments about the 25 undesirable torque to said sensitive element tending to
vertical axis 10 in a manner similar to that described with
cause an undesirable output signal, and means for apply
respect to the thrust bearing 18‘ of FIG. 1. ‘Periodically
ing a force to said rolling anti-friction members in a
reversing the direction of rotation of the intermediate race
direction and of a magnitude to effectively substantially
eliminate said undesirable torque.
83 reduces any small remaining random moments to the
point where they are negiligible.
2. In combination, a sensitive element, means respon
While the invention has been described with respect to
sive to the movement of said sensitive element for pro~
a mechanical means for applying a force to a ball retainer
33 in order to substantially eliminate undesirable friction
moments around the vertical axis it} of a sensitive element,
i.e., gyroscope 9, it will be understood that the force or
drag may he applied to the retainer 33 by other means
including (1) an eddy current brake, (2) an electromag
netic device, (3) a permanent magnetism arrangement,
(4) a ?uid device or (5) supporting the retainer on a
bearing. Further, it will be appreciated that the force
may be applied directly to the bearing balls associated
with the inner race, i.e., balls 32 and 82 by means of mag
netism or by a drag applied directly to the bearing balls.
During accelerations, the normal forces at the contact
areas of the balls will change because the weight of the
instrument changes. This will cause a change in the
friction forces, and possibility a change in the friction
moments acting on the instrument. To compensate for
this, the following acceleration sensitive eifects may be
made use of: (l) The retainer mass will itself exert a
force on the balls as a function of acceleration. (2)
Under accelerations, relative displacement will occur be
tween the bearing balls (and the retainer) and the means
for applying the drag. This displacement may be made
use of in all embodiments mentioned in the preceding
paragraph. (3) If ?uids or gases are used, (a) the ?ow
of ?uid may be metered as a function of acceleration, (b)
the gap between the retainer and the stationary element
may be varied, thereby varying the shear force. (4) The
point of application of the force providing the drag may
be varied, thereby varying the drag torque on the retainer.
(5) if an electromagnetic device is used, the current may
be made a function of the acceleration.
The undesirable friction moment described above tends
viding an output signal in accordance therewith, bearing
means rotatably supporting said element, said bearing
means including an inner race, an outer race, rolling anti
frietion members disposed between said races and retainer
means cooperative with and separating said rolling anti
friction members, at least said bearing means tending to
apply an undesirable torque to said sensitive element tend
ing to cause an undesirable output signal, and means for
applying a force to said retainer means in a direction and
of a magnitude to effectively substantially eliminate said
undesirable torque.
3. In combination, a sensitive element having an out
put axis, bearing means supporting said element for rota
tion about its output axis, said bearing means including
an inner race, an outer race, rolling anti-friction members
disposed between said races, and retainer means coopera
tive with said separating said rolling anti-friction mem
bers, said outer race being rotatable and when rotating
said bearing means tends to apply an undesirable torque
about said output axis, and means for applying a force
to said retainer means in a direction and of a magnitude
to effectively substantially eliminate said undesirable
torque about said output axis.
4. In a gyroscopic device, a sensitive element having
a vertical output axis, means including thrust bearing
means supporting said element for rotation about its ver
tical output axis, said thrust bearing means including an
inner race, an outer race, balls disposed between said
races, and a ball retainer cooperative with and separating
said balls, said outer race being rotatable and when ro
tating said balls tends to apply an undesirable torque about
said output axis, and means for applying a force to said
retainer having a magnitude and a direction to effectively
to vary with the attitude of the gimbal thus by varying 65 substantially eliminate said undesirable torque about said
output axis.
the drag on the retainer as a function of the gimbal’s at
5. In a gyroscopic device, a sensitive element having
titude substantially zero friction is theoretically possible
a vertical output axis, means including thrust bearing
at all times.
means supporting said element for rotation about its ver
While the invention has been described with respect
tical output axis, said thrust bearing means including an
to applying sufficient force to counteract the undesirable
friction torques around the vertical axis 10 of the gyro
inner race, an outer race, balls disposed between said
scope 9, the present invention may also be utilized to
races, and a ball retainer cooperative with and separating
apply more than enough force to overcome the undesired
said balls, said outer race being rotatable and when ro
friction torques. In this Way the present invention may
tating said balls tend to apply an undesirable torque about
be utilized to torque the gyroscope in lieu of a conven 75 said output axis, means cooperative with said sensitive
3,082,629"
.
element tending to apply an additional undesirable torque
about said output axis, and means for applying a force to
said retainer having a magnitude and a direction to ef
fectively substantially counteract the net undesirable
torque about said output axis.
6. In combination, a pair of aligned spaced radial bear
ings, a loaded shaft rotatably restrained in said bearings
for rotation about a normally vertical axis, said bearings
including an intermediate element disposed in coopera
tive relative rotatable relationship between inner and 10
outer anti-friction elements, thrust bearing means sup
porting said shaft for rotation about said vertical axis,
said thrust bearing means including an inner race, an
outer race, balls disposed between said races and a ball
8
7. In combination, an element, bearing means for ro
tatably supporting said element for rotation about an
axis thereof, means tending to apply an undesirable torque
to said element about said axis, said bearing means in
cluding anti-friction means cooperative with said element,
and means for applying a force to said anti~friction means
in a direction and of a magnitude to effectively substan
tially eliminate said undesirable torque about said axis.
8. In combination, an element, bearing means for ro
tatably supporting said element for rotation about an
axis thereof, means including said bearing means tending
to apply an undesirable torque to said element about said
axis, said bearing means including rolling anti—friction
means cooperative with said element, and means for apply
retainer cooperative with and separating said balls, said 15 ing a force to at least a portion of said rolling anti
friction means in a direction and of a magnitude to ef
intermediate elements of said radial bearings, and said
fectively substantially eliminate said undesirable torque
outer race of said thrust bearing being rotatable and
about said axis.
when rotating said balls tend to apply an undesirable
torque about said vertical axis, means for continuously
rotating and periodically reversing the directions of rota 20
tion of both intermediate elements simultaneously in op
posite directions and said outer race of said thrust bear
ing means, and means for applying a force to said ball
retainer having a magnitude and a direction to effectively
substantially eliminate said undesirable torque about said 25
vertical axis.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,048,834
Young ______________ __ July 28, 1936
2,209,735
2,577,942
2,662,410
Lauck _______________ __ July 30, 1940
Agins _______________ __ Dec. 11, 1951
Ballard et al ___________ __ Dec. 15, 1953
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